Still projector with single-acting compensation device

Abstract

In order to compensate for the "Keystone-effect," a still projector is equipped with a vertically adjustable lens holder, which is coupled by a sliding pivot to a pivotable lamp housing. The lamp housing has a pair of arms projecting therefrom, which have slots extending therein which, in turn, register with pins positioned in the lens holder. The pins are located adjacent the rear nodal plane of the lens, and are aligned with an axis, which intersects the optical axis of the lens. Upon adjusting the holder vertically, the lamp housing will tilt to insure that the projected image will angularly conform to the original.

I claim: 
     
       1. A still projector equipped with a device for compensating for angular errors caused by projection deviation from the normal in a vertical plane, wherein the device includes means for rendering possible vertical displacement of the lens of the still projector perpendicular to its optical axis, a lighting means pivotal in a vertical plane about the centre of a transparent original, and means for automatically directing the paraxial ray path of the lighting means to the rear nodal point of the lens, wherein the improvement comprises: a projector housing (13);   a lens means having a rear model plane, a holder for said lens means (12), wherein said holder (14) is mounted in said housing (13);   a set screw (15) rotatably supported in said housing (13) and threaded with said holder (14);   guide means (17) registered with said holder (14) for limiting said holder (14) to vertical displacement upon rotating said set screw (15), in order to vertically displace said lens (1);   a lamp housing (26) having sides and rotatably supported by the projection housing (13) for rotation about a horizontal axis located through the center (M) of the transparent original (2), in a plane defined by the original;   lamp and optical means (5-10) mounted in said lamp housing for defining an optical axis (26);   coupling means for coupling the lamp housing (26) to the holder (14), wherein said coupling means includes at least one driving arm (30), extending from said lamp housing (26), which engages said holder (14) with a sliding pivot means (25,31), wherein the axis (25) of said pivot is intersected by, and normal to said optical axis, and wherein the axis of said pivot means is in the rear nodal plane (12) of the lens means (1).   
     
     
       2. The still projector of claim 1, wherein the sliding pivot means (23,31) is formed by a slot (31) extending in said driving arm (30), and a pin (25) extending from said holder and in alignment with said axis of said pivot means. 
     
     
       3. The still projector of claim 2, wherein there is a pair of driving arms (30), each of which has a slot (31) registered with a pair of pins (25) extending in alignment with the axis of said pivot means. 
     
     
       4. The still projector of claim 3, wherein the driving arms (30) are integral with sides of the lamp housing (26), and extend through recesses (32) in the lens means holder (14). 
     
     
       5. The still projector of claim 1, characterized in that the mounting of the lamp housing (26) includes lateral arc-shaped projections (27), which are provided on the sides of the lamp housing and are rotatably supported in corresponding bearing cups (28) provided on the sides of the projector housing. 
     
     
       6. The still projector of claim 5, wherein the driving arms (30) are integral with sides of the lamp housing (26), and extend through recesses (32) in the lens means holder (14).